The present invention relates to measuring devices utilized to measure and record the amount of time during a day that direct sun light strikes a sensor, and more particularity to sun meters and a method of utilizing a plurality of meters to determine specific locations in a given area that receive relatively more direct sun light than others and the quantities received of direct sun light at each location.
A number of devices have been developed which utilize light sensors, including photoresistive elements. U.S. Pat. No. 4,015,116 shows a device which measures the total solar radiation over a given time. While this device may be useful for some applications, it does not teach or suggest a way to record direct sun striking a sensor for a given time.
U.S. Pat. No. 4,110,049 discloses a radiation measuring device for recording radiation levels on a graph with time as an axis of the graph and intensity as a second axis. FIG. 6 of the ""049 patent shows a graphical display of a hypothetical cloudy day. It would be difficult to determine the amount of direct sun upon a sensor based upon this graph. Furthermore, there is no teaching that such a determination should be made.
U.S. Pat. No. 4,161,124 shows a solar energy measuring device that measures the total amount of solar energy received in a given time period utilizing a frequency generated by a frequency controlled-frequency oscillator which alter frequency according to the strength of light impacting upon the sensor.
U.S. Pat. No. 4,218,139 shows a device which measures and displays the total solar energy impacting a sensor cell in a given period by counting pulses in an electrical pulse train.
U.S. Pat. No. 4,609,288 shows a device which measures the strength of the radiation from the sun at a specific point in time.
U.S. Pat. No. 5,784,303 shows a light sensing device having a sampling signal generator and a measuring device wherein the sampling signal is utilized when not measuring the light.
U.S. Pat. Nos. 5,717,487 and 6,107,998 show devices utilized to obtain information to orient sensor cells relative to a light source to maximize the effectiveness of the sensor cells.
Most, or all, of these prior art devices utilize light sensors. Typical light sensors allow current to flow through them proportional to the amount of light they receive. For full sun, some light sensors provide a relatively high voltage. At other daylight conditions, the voltage will be less than at full sun. In no light situations, the light sensor records low voltage and some light sensors may even turn themselves off. Some light sensors operate utilizing solar energy. Others operate utilizing a more traditional power source. Newark Electronics offers a plurality of these type sensors in their current catalogue at page 570, as well as on their website at www.newark.com.
Although devices utilizing sensors have been developed in the prior art which measure the strength of sunlight and record the strength of sunlight over time, there is not believed to have been any effort undertaken to measure the time, or average time during a set period, of direct sunlight upon a particular location. This information is believed to be helpful to determine what types of plants will thrive at a specific location. Furthermore, there is not believed to have been any effort to determine within a specific area, the locations which receive relatively more direct sun than others and the quantities of direct sunlight received.
Consequently, it is a primary object of the present invention to provide a sun meter which measures the time of direct sunlight striking a sensor in a single day.
It is another object of the invention to provide a meter capable of determining an average daily amount of direct sun striking a sensor over a period of days.
It is a further object of the present invention to provide a meter configured to store the amount of direct sun light received for a number of days for display to and/or recall by a user.
It is still a further object of the invention to provide a method of utilizing a plurality of sun meters adapted to measure the amount of time of direct sun received in a given period, or average daily direct sun, in order to determine the location(s) of relative more direct sun in a given area as well as the amount of direct sunlight at the location(s).
It is a further object of the invention to provide a meter capable of having multiple preset thresholds to compare to day/night light thresholds as well as to provide a pre-set direct sun value threshold for evaluating whether and how much direct sunlight is received during a daytime period.
Accordingly, the present invention provides at least one, and preferably, a plurality of sun meters and method of their use. The sun meter(s) includes a light sensor which measures the amount of light striking the sensor. Upon activation, if the light striking the meter reaches a first pre-set threshold corresponding to direct sunlight, the meter counts the time. If the light striking the meter is below the first pre-set level, the meter does not count the time. If the light striking the meter is below a second pre-set level corresponding to night, the meter enters a night mode. A microprocessor counts the time above the first pre-set level for each day and stores the daily amount of direct sun light.
Once the meter(s) have been in position for a desired length of time, the meters may be read. The meters preferably record the amount of time, such as the number of hours, of direct sunlight for each day the meter(s) were activated. Furthermore, the meters preferably track the average amount of direct sun light since the activation of the meter.
When utilizing multiple sensors or meters, various locations in a given area may be evaluated to determine which locations receive relatively more direct sun than others. This information has been found to assist in determining the types of plants which will flourish in particular locations in the given area.